Wafer-scale and doping-tunable p-type semiconducting monolayer WSi₂N₄ film

Monolayer WSi₂N₄ has been predicted to be a high-performance p-type semiconductor with high hole mobility, high on-state current density, high strength, and high thermal conductivity. Achieving large-area growth of monolayer WSi₂N₄ with controlled doping is a prerequisite for the scalable integration of device applications. However, only micrometer-sized monolayer WSi₂N₄ domains have been synthesized so far. Here, we report the growth of wafer-scale monolayer WSi₂N₄ films with submillimeter domains by chemical vapor deposition using a liquid Au/W bilayer as the growth substrate, with a growth rate three orders of magnitude higher than previously reported values. This method also enables efficient modulation of carrier doping concentration from 5.8 × 10¹² cm^-2 to 3.2 × 10¹³ cm^-2 through in situ defect engineering. This doping-tunable monolayer WSi₂N₄ exhibits p-type semiconducting characteristics with a bandgap of ∼2.25 eV, achieving an on/off current ratio of 5.4 × 10⁴ at a low doping level and a high on-state current density (∼150 μA μm^-1) and a low contact resistance (0.95 kΩ μm) for heavily doped material. Moreover, it has excellent stability and ultrahigh Young's modulus (∼538 GPa) and strength (∼62 GPa). This work paves the way for the applications of monolayer WSi₂N₄ as a promising p-type channel material in 2D complementary metal-oxide-semiconductor integrated circuits.